Process of dyeing



Patented Nov. 24, 1931 UNITED STATES PATENT OFFICE RICHARD G. KNOWLAND, OF WOLLASTON, MASSACHUSETTS, ASSIGNOR TO NASHUA MANUFACTURING COMPANY, OF NASI-IUA, NEW HAMPSHIRE, A CORPCRA'I'ION OF NEW HAMPSHIRE No Drawing.

This invention relates to processes of dyeing and more especially to the dyeing of cotton yarn, fabrics, or fibre, hereinafter referred to generically as cotton goods.

When vat colors are deposited on cotton in the ordinary process of mill dyeing, a certain amount of loose color is left on the surface of the goods. This loose color is subsequently removed by a soaping process which acts both to loosen and carry away the unattached dye particles and also to improve the lustre and give added brilliance to the dyed material.

In dyeing with the indanthrene blues it is found that the subsequent soaping of the goods produces a shift in color from a normal greenish blue shade toward a reddish blue, this color change producing a final shade which is not as desirable in the trade as the greenish cast that is characteristic of these colors.

The present invention deals with the prob lem presented by these conditions and aims to devise a simple and economical way of preventing the change in color above described.

I have found that if a small percentage of an oxidizing agent is added to the soaping bath,the tendency of the greenish blue shades to change in color is checked. Oxidizing agents suitable for this purpose include calcium hypochlorite, sodium hypochlorite, hydrogen peroxide, sodium peroxide, and others. I have obtained very satisfactory results by using sodium hypochlorite in quantities varying from two-tenths of one percent. to five-tenths of one percent. of the weight of the goods being treated.

The addition of an oxidizing agent tothe soaping bath as above described is of further advantage in permitting a much greater variation in the time and temperature at which the soaping treatment is carried on without danger of producing a color shift than otherwise would be possible.

While I have herein disclosed a preferred method of practicing my invention, it will be evident that the invention is not limited to the precise details of the process disclosed.

Having thus described my invention, what I desire to claim as new is: V

1. That improvementin methods of dyeing PROCESS OF DYEING Application filed January 30, 1928. Serial No. 250,733.

2. That improvement in methods of dyeing with indanthrene blues which consists in performing the dyeing and subsequent soaping operationsin any suitable manner, and using a sufficient percentage of sodium hypochlorite in the soaping bath to prevent any substantial shift from a normal color.

3. The herein described process consisting in dyeing goods with an indanthrene blue dye, and subsequently removing surplus dye by soaping the goods in a bath containing a quantity of an oxidizing agent equal to from two-tenths of one percent. to one percent. of the weight of the goods being dyed.

4. The herein described process consisting in dyeing goods with an indanthrene blue dye, and subsequently soaping the goods in a bath containing a quantity of sodium hypochlorite equal to from two-tenths of one percent. to one percent. of the weight of the goods being dyed.

RICHARD G. KNOWLAND. 

